Entrainment of breathing rate to movement frequency during work at two intensities

Abstract

Ten males and six females exercised on an electrically braked cycle ergometer. Three conditions were tested: preferred pedal frequency with no cues; preferred frequency established by listening to a metronome and preferred frequency maintained by watching a digital display. Each condition was performed at a low workload and a high workload, and this set of tests was repeated once. During each test, computer sampling of pedal and breath information occurred, and the relationship of breath signal occurrences to pedal signals was plotted by a post stimulus histogram program. Fourier analysis of psh data (Time Series Spectrum Estimation) decomposed each histogram into it's frequency components. The magnitude of the frequency at the fundamental of the pedal period (F1), and it's first harmonic (F2), were assessed using F ratios. For retest results, preferred condition, 100% of subjects were entrained for both low and high workloads. With the metronome, 87% were entrained at the low workload and 94% at the high workload. For both workloads, 94% were entrained when watching a digital printout of pedal frequency. For preferred pedal rate, at the two workloads tested, the results of this study strongly support the existence of entrainment, and provide evidence for neurogenic input to ventilatory control during steady state work.